类指针

发布于 2015-08-16 14:55:38 | 77 次阅读 | 评论: 0 | 来源: 网络整理

一个指向类是做完全相同的方式作为一个指向结构和存取指针的成员使用成员访问运算符类- >操作符，就像结构体指针。与其它的指针一样，必须在使用前初始化指针。

让我们试试下面的例子就明白了指针指向一个类的概念：

import std.stdio;

class Box
{
   public:
      // Constructor definition
      this(double l=2.0, double b=2.0, double h=2.0)
      {
         writeln("Constructor called.");
         length = l;
         breadth = b;
         height = h;
      }
      double Volume()
      {
         return length * breadth * height;
      }
   private:
      double length;     // Length of a box
      double breadth;    // Breadth of a box
      double height;     // Height of a box
}

void main()
{
   Box Box1 = new Box(3.3, 1.2, 1.5);    // Declare box1
   Box Box2 = new Box(8.5, 6.0, 2.0);    // Declare box2
   Box *ptrBox;                // Declare pointer to a class.

   // Save the address of first object
   ptrBox = &Box1;

   // Now try to access a member using member access operator
   writeln("Volume of Box1: ",ptrBox.Volume());

   // Save the address of first object
   ptrBox = &Box2;

   // Now try to access a member using member access operator
   writeln("Volume of Box2: ", ptrBox.Volume());
}

让我们编译和运行上面的程序，这将产生以下结果：

Constructor called.
Constructor called.
Volume of Box1: 5.94
Volume of Box2: 102